[Mg/Fe] as a function of [Fe/H] obtained from high-resolution spectroscopy of individual stars in the Milky Way or in Local Group dSphs. The yellow shaded region shows the 1 − σ dispersion around the mean [Mg/Fe] for stars with a metallicity below −2.5. The data are obtained from high spectroscopy abundances determination: Fornax (Shetrone et al. 2003; Tafelmeyer et al. 2010; Letarte et al. 2010), Sculptor (Shetrone et al. 2003; Tafelmeyer et al. 2010; Starkenburg et al. 2013; Jablonka et al. 2015; Hill, in prep.), Sextans (Shetrone et al. 2001; Aoki et al. 2009; Tafelmeyer et al. 2010), Carina (Shetrone et al. 2003; Venn et al. 2012; Lemasle et al. 2012), ComaBer (Frebel et al. 2010), Bootes (Norris et al. 2010), LeoI (Shetrone et al. 2003), Hercules (Koch et al. 2008), Uma (Frebel et al. 2010), UMi (Shetrone et al. 2001; Cohen & Huang 2010), Draco (Shetrone et al. 2001; Fulbright et al. 2004; Cohen & Huang 2009), and MilkyWay (Gratton et al. 2003; Cayrel et al. 2004; Venn et al. 2004; Honda et al. 2004; Gehren et al. 2006; Reddy et al. 2006; Andrievsky et al. 2010; Cohen et al. 2013; Aoki et al. 2014). All values have been scaled to the solar abundances of Asplund et al. (2009).